Ship hunting for more 'pings' in plane search

PERTH, Australia — Search crews have failed to relocate faint sounds heard deep in the Indian Ocean, possibly from the missing Malaysian jetliner's black boxes whose batteries are at the end of their life.

Angus Houston, the retired Australian air chief marshal who is heading the search far off Australia's west coast, said sound locating equipment on board the Ocean Shield has picked up no trace of the signals since they were first heard late Saturday and early Sunday. The signals had sparked hopes of a breakthrough in the search for Flight 370.

Finding the black boxes quickly is critical, because their locator beacons have a battery life of only about a month — and Tuesday marks exactly one month since the plane vanished. Once the beacons blink off, locating the black boxes in such deep water would be an immensely difficult, if not impossible, task.

"There have been no further contacts with any transmission and we need to continue (searching) for several days right up to the point at which there's absolutely no doubt that the batteries will have expired," Houston said.

If, by that point, the U.S. Navy listening equipment being towed behind the Ocean Shield has failed to pick up any signals, a sub on board the ship will be deployed to try and chart out any debris on the sea floor. If the sub maps out a debris field, the crew will replace its sonar system with a camera unit to photograph any wreckage.

Houston's comments contradicted an earlier statement from Australia's acting prime minister, Warren Truss, who said search crews would launch the Bluefin 21 autonomous sub on Tuesday. A spokesman for Truss said the conflicting information was a misunderstanding, and Truss acknowledged the sub was not being used immediately.

The towed pinger locator detected late Saturday and early Sunday two distinct, long-lasting sounds underwater that are consistent with the pings from an aircraft's black boxes — the flight data and cockpit voice recorders, Houston said.

"This is the most positive lead, and rest assured we are pursuing it very vigorously," Defense Minister David Johnston said.

Still, officials warned it could take days to determine whether the sounds were connected to the missing plane, which vanished March 8 on a flight from Kuala Lumpur, Malaysia, to Beijing with 239 on board.

"This is an herculean task — it's over a very, very wide area, the water is extremely deep," Johnston said. "We have at least several days of intense action ahead of us."

Houtson said finding the sound again was critical to narrowing down the search area before the sub can be used. If the vehicle went down now with the sparse data collected so far, it would take "many, many days" for it to cover all the places the pings might have come from.

"It's literally crawling at the bottom of the ocean so it's going to take a long, long time," Houston said.

In this April 7 photo provided by the Australian Defense Force Able Seaman Clearance Diver Michael Arnold is towed by a fast response craft from the Australian Defense's ship Ocean Shield as he scans the water for debris of the missing Malaysia Airlines Flight 370 in the southern Indian Ocean.